I'll take Super Mario 64 any day over nearly any Mario game that came afterwards, short of maybe Odyssey which is like a spiritual successor to it practically. It might not hold up the best with a few aspects of its controls, but for the time it released, it nailed 3D platforming pretty much right out of the gate and it's charming as all heck still.
Nintendo for me is a mixed bag over the years. There's almost always good games in any generation short of maybe the Wii for me, which is their worst time personally. I was big into them from NES to N64, didn't get into Gamecube much, and then while I got a Wii at launch, I very quickly fell off it and sold it like 6 months later. Wii mote controls are awful, currently not sure if I hate the joycons or wii-mote more. Loved the Wii U as a system despite it failing, and while initially I was very hyped for the Switch and had a good first year, but the amount of Wii U ports for filling the game releases and not liking a lot of what came afterward soured me on the system, though I still think it's a neat piece of hardware. There's so much to love and hate about Nintendo, especially nowadays, but they are still a company I can find to bring out enjoyable games.
For Mario in general, I loved Mario quite abit up till that DS/Wii era, my favorite 2D Mario being Super Mario World, and Super Mario 64 being my favorite Mario overall, but when Galaxy and the New Super Mario Bros games came out, they felt like a regression of the series to me. They aren't bad games, Mario is never bad, but by the time Super Mario 3D Land and World came out, there was basically no real difference between them, both types of Mario were Super Mario 3 rehashes but the cameras were different. It wasn't till Odyssey came out that I got super excited for Mario again and really loved my time with it.